Dear friend,you can mix gypsem to the soil,fill it with water and plough it in water,after a day or two drain the water out.Alternatively green manure like 'dencha' is very effective.Apart from it if you can get straw of paddy,mix it in the soil and fill with water and let it decay.It will help you to solve your problem.Remember your pH is alkaline so I dont agree with treatment with Lime as it is alkaline and only acids can neutralise alkalies,as somebody suggested.